The present invention relates to a cataplasm containing vitamin C or a derivative thereof. More specifically, the present invention relates to a cataplasm comprising a crosslinked polymer gel containing vitamin C or a derivative thereof and a support.
Water-soluble adhesive ingredients are widely and routinely used today in conventional cataplasms such as antiphlogistic and analgetic cataplasms (plaster for external skin), moisture retention cosmetic pack and cooling gel sheets. They are formed by mixing kaolin or glycerin as a base with water-soluble polymer materials such as sodium polyacrylate or carboxymethylcellulose sodium, various active ingredients, water and so forth, and molding them, while its shape-retainability is secured by using a metal crosslinking agent.
Vitamin C or a derivative thereof has long been known to have an effect for preventing abnormal pigmentation by inhibiting skin melanin production, and it has been attempted to add vitamin C or a derivative thereof to cataplasms such as a cosmetic pack as an active ingredient for obtaining a skin-whitening effect. However, there is a problem that, when vitamin C or a derivative thereof is added to an adhesive cataplasm, a stable gel cannot be formed since water-soluble polymers are not crosslinked due to interaction of vitamin C or a derivative thereof and a metal crosslinking agent and thus the materials cannot be molded as a cataplasm.
As a result of efforts devoted to solve this problem, it was found that a gel-like cataplasm having favorable shape-retainability could be obtained by blending two kinds of substances selected from magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride as crosslinking agents with a mixture of a water soluble polymer, glycerin, kaolin, water and so forth, and thus the present invention was accomplished.
That is, the present invention provides a cataplasm comprising crosslinked polymer gel containing vitamin C or a derivative thereof and a support, wherein the gel is formed by crosslinking a polymer with two kinds of substances selected from magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride.
In the present invention, the polymer preferably consists of one or more kinds of materials selected from the group consisting of gelatin, gum arabic, glucomannan, xanthan gum, tragacanth gum, polyacrylic acid, sodium polyacrylate, polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymer, carboxymethylcellulose sodium, hydroxypropylcellulose, methylcellulose, ethylcellulose, methyl vinyl ether/maleic anhydride copolymer, sodium polyalginate and polyethylene oxide.
In the present invention, the content of vitamin C or a derivative thereof is preferably 0.01-10 parts by weight per 100 parts by weight of the crosslinked polymer gel.
In the present invention, the sum of the contents of the two kinds of crosslinking agents selected from magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride is preferably 0.5-5 parts by weight per 100 parts by weight of the crosslinked polymer gel.
In the present invention, the polymer content is preferably 1-40 parts by weight per 100 parts by weight of the crosslinked polymer gel.
Further, pH of the gel used for the cataplasm of the present invention is preferably in the range of 5.5-8.5. Moreover, the gel of the cataplasm of the present invention preferably further contains a polyhydric alcohol.
The cataplasm of the present invention containing vitamin C or a derivative thereof has excellent shape-retainability, since gel is formed by crosslinking of the polymer due to the inclusion of the two kinds of substances selected from magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride.
Hereafter, the present invention will be explained in more detail.
The present invention provides a cataplasm comprising crosslinked polymer gel containing vitamin C or a derivative thereof and a support, wherein the gel is formed by crosslinking a polymer with two kinds of substances selected from magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride. That is, the cataplasm of the present invention is characterized by containing vitamin C or a derivative thereof, two kinds of substances selected from magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride and polymer. This cataplasm can provide various effects of vitamin C or a derivative thereof due to the inclusion of vitamin C or a derivative thereof as an active ingredient, and can show superior shape-retainability and adhesion since the polymer is crosslinked to form a gel even in the presence of vitamin C or a derivative thereof due to the inclusion of two kinds of substances selected from magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride as crosslinking agents. Each of these ingredients will be explained below.
 less than 1 greater than  Vitamin C or Derivative Thereof
The cataplasm of the present invention containing crosslinked polymer gel contains vitamin C, i.e., L-ascorbic acid, or a derivative of L-ascorbic acid. Examples of derivatives of L-ascorbic acid include various salts of L-ascorbic acid such as sodium L-ascorbate and L-ascorbyl magnesium phosphate, esters such as L-ascorbyl palmitate, L-ascorbyl stearate and isopropyl vitamin C and so forth. These vitamin C and derivatives thereof can be used each alone, or as a combination of two or more kinds of them. The amount thereof is preferably 0.01-10 parts by weight, more preferably 1-5 parts by weight, per 100 parts by weight of the crosslinked polymer gel. Since the cataplasm of the present invention contains vitamin C or a derivative thereof, there can be obtained various effects derived from vitamin C, for example, a skin-whitening effect obtained by inhibition of skin melanin production and so forth. As described above, the cataplasm of the present invention contains vitamin C or a derivative thereof as an active ingredient, but can also contain other active ingredients. Preferred examples of such active ingredients include sodium hyaluronate, vitamin A, collagen and so forth.
 less than 2 greater than  Polymer Material
The cataplasm of the present invention contains a polymer. Examples of the polymer include natural polymers such as gelatin, gum arabic, glucomannan, xanthan gum and tragacanth gum, polyacrylic acid, sodium polyacrylate, polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymer, cellulose derivatives such as carboxymethylcellulose sodium, hydroxypropylcellulose, methylcellulose and ethylcellulose, water-soluble synthetic polymers such as methyl vinyl ether/maleic anhydride copolymer, sodium polyalginate and polyethylene oxide and so forth. The molecular weight of these polymers is not particularly limited.
These polymers may be used each alone or as a combination of two or more kinds of them. Among these polymers, polyacrylic acid and sodium polyacrylate added with other polymers are preferably used. The amount of the polymer can be appropriately selected depending on the kind of polymer to be selected, but it is preferably 1-40 parts by weight, more preferably 5-20 parts by weight, per 100 parts by weight of the crosslinked polymer gel. A cataplasm having favorable shape-retainability and adhesion can be prepared by blending such an amount of the polymer.
 less than 3 greater than  Crosslinking Agent
The cataplasm of the present invention containing crosslinked polymer gel contains two kinds of substances selected from magnesium aluminometasilicate, dried saluminum hydroxide gel and aluminum chloride as crosslinking agents.
The combination of magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride for use in the present invention can be appropriately selected depending on the attaching site or desired adhesion of products. As magnesium aluminometasilicate, for example, Neusilin available from Fuji Chemical Industry Co., Ltd. can be used. As dried aluminum hydroxide gel, the dried aluminum hydroxide gel available from Kyowa Chemical Industry Co., Ltd. can be used. As aluminum chloride, aluminum chloride available from Wako Pure Chemical Industries, Ltd. can be used. Two kinds of substances can be appropriately selected from the above depending on the kind of polymer to be selected or required adhesion.
Chemical formulae of these crosslinking agents for use in the present invention are shown below. Magnesium aluminometasilicate: Al2O3.MgO.2SiO2.xH2O Dried aluminum hydroxide gel: Al2O3.nH2O Aluminum chloride: AlCl3.6H2O
The amount of the two kinds of substances selected from magnesium aluminometasilicate, dried aluminum hydroxide gel, aluminum chloride is preferably 0.5-5 parts by weight, more preferably 0.7-3 parts by weight, per 100 parts by weight of the crosslinked polymer gel. The polymer can be crosslinked to form a gel by blending two kinds of substances selected from magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride with the polymer in a proportion of 0.5-5 parts by weight even when vitamin C or a derivative thereof is contained, and thus a stable cataplasm which can maintain shape-retainability of the gel for a long period of time can be obtained.
When vitamin C or a derivative thereof is added to such a cataplasm, the polymer is not usually crosslinked due to interaction between vitamin C or a derivative thereof and the crosslinking agent. However, the polymer is favorably crosslinked by using the two kinds of substances selected from magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride as crosslinking agents.
 less than 4 greater than  Cataplasm
The cataplasm of the present invention comprising the crosslinked polymer gel contains an appropriate amount of water in addition to the aforementioned ingredients. The content of water is preferably 20-80 parts by weight, more preferably 30-60 parts by weight, per 100 parts by weight of the crosslinked polymer gel.
The cataplasm preferably further contains a polyhydric alcohol such as glycerin, sorbitol, propylene glycol, 1,3-butylene glycol or ethylene glycol among various additives for use in usual cataplasms. Among these polyhydric alcohols, glycerin, sorbitol or propylene glycol is preferably used. The content of polyhydric alcohol is preferably 5-40 parts by weight, more preferably 10-30 parts by weight, per 100 parts by weight of the crosslinked polymer gel. By blending these polyhydric alcohols in an amount within an appropriate range, shape-retainability and adhesion can be stably maintained for a long period of time.
Further, the cataplasm of the present invention preferably contains an inorganic substance such as kaolin, bentonite or titanium oxide. Kaolin is preferably used among these inorganic substances. The content of the inorganic substance is preferably 0.1-20 parts by weight, more preferably 2-10 parts by weight, per 100 parts by weight of the crosslinked polymer gel. By blending these inorganic substances, cohesion of the cataplasm or plaster can be improved.
The cataplasm of the present invention may optionally contain various additives for use in usual cataplasms as required. Examples of such additives include, for example, alcohols such as ethanol and isopropanol, antioxidants such as sodium hydrogensulfite and erythorbic acid, preservatives such as methylparaben and propylparaben, surfactants such as hydrogenated caster oil, oils such as hohoba oil or eucalyptus oil, chelating agents such as sodium edetate, pH regulators such as sodium hydroxide or tartaric acid, perfumes, coloring matters and so forth. The kinds of these additives are not particularly limited, and those conventionally used in cataplasms, packs, ointments, gels, creams and so forth can be appropriately selected and used. The contents thereof are not also particularly limited, and can be adjusted depending on the purpose.
Further, pH of the cataplasm of the present invention is preferably in the range of 5.5-8.5, more preferably 6.0-8.0. When the cataplasm is used in the range of pH 5.5-8.5, it shows favorable shape-retainability, adhesion and stability for long-term storage. The pH of the cataplasm can be measured by using a usual pH meter, for example.
The cataplasm of the present invention is used as a cataplasm comprising a support as described below from viewpoints of ease of use and obtaining continuous effects of vitamin C or a derivative thereof or other active ingredients.
A cataplasm comprising a support can be prepared, for example, as described below. That is, a plaster (gel) is prepared as a paste by uniformly mixing the aforementioned respective ingredients, coated and spread on a support such as paper, non-woven fabric or plastic film in a conventional manner to obtain a cataplasm. To protect the cataplasm, a release paper sheet may be stuck on the surface thereof, and the cataplasm may be cut into a predetermined size for use. The method of preparing the cataplasm is not particularly limited, and methods usually used for the preparation of cataplasms can be appropriately used.
As the support, paper, non-woven fabric, plastic film or the like can be used and is not particularly limited. However, non-woven fabric or knit is preferably used.
By using two kinds of substances selected from magnesium aluminometasilicate, dried aluminum hydroxide gel and aluminum chloride as crosslinking agents for a paste containing vitamin C or a derivative thereof, water-soluble polymer and water in the cataplasm of the present invention, the polymer can be crosslinked to form a stable gel. It was found that this cataplasm was hardly solidified, did not cause separation due to dehydration, exudation from back face of the support, overflow from the periphery of the support and so forth, and had stable shape-retainability.